Two tiny spheres carrying charges $1.8 \mu C$ and $2.8 \mu C$ are located $40 \ cm$ apart. The potential at the mid-point of the line joining the two charges is:

$A$ charge $Q$ is placed at each corner of a cube of side $r$. The potential at the centre of the cube is ($\epsilon_0$ = permittivity of free space).

Two small equal point charges of magnitude $q$ are suspended from a common point on the ceiling by insulating massless strings of equal lengths. They come to equilibrium with each string making an angle $\theta$ from the vertical. If the mass of each charge is $m$,then the electrostatic potential at the centre of the line joining them will be $\left( \frac{1}{4\pi \epsilon_0} = k \right).$

$A$ proton is accelerated through a potential difference of $1 \,V$. The kinetic energy $(KE)$ of the proton will be $....... \,eV$.

The potential of a large liquid drop formed when eight identical small liquid drops are combined is $20 \,V$. What was the potential of each single small drop (in $\,V$)?

$A$ proton is about $1840$ times heavier than an electron. When it is accelerated by a potential difference of $1\, kV$,its kinetic energy will be......$keV$.